Lock-stitch sewing machine convertible to a chain stitch sewing machine



3,428,008 ERTIBLE TO Sheet INVENTGR ATTORNEY R. CASAS-ROBERT -STITCH SEWING MACHINE CONV A CHAIN STITCH SEWING MACHINE Feb. 18, 1969 LOCK Filed March 20. 1967 R. CASAS-ROBERT S'IITCH 5 LOCK EWING MACHINE CONVERTIBLE TO A CHAIN STITCH SEWING MACHINE Filed March 20. 1967 INVENTOR RAMON C'Asns ROBERT BY 5%, -41, W

ATTORNEY United States Patent 5,427/ 66 US. Cl. 112-168 10 Claims Int. Cl. Db 23/00 ABSTRACT OF THE DISCLOSURE An improved sewing machine includes a loop-guide element arranged so as to enable the machine to be used either for chain-stitch sewing or for normal sewing with two threads. The element may be an arm having a forked end and may be elastically mounted on a support plate adjustably attached to the driving or control lever of the feeding mechanism.

The present invention relates to sewing machines. More particularly it relates to sewing machines for both chainstitch sewing and normal sewing with two threads.

It is an object of the present invention to provide an improved machine of the type comprising a frame for 1 supporting the driving mechanism for the needle and for the driving mechanism of the transporter, the lower part of the frame including a shuttle device and rotating hook for the formation of a loop with the upper thread drawn by the needle and the knotting of this upper thread to a lower thread paid out by the bobbin for normal sewing with two threads, which machine can alternatively be readily adapted to chain-stitch sewing.

According to the invention there is provided a sewing machine, comprising a supporting frame for a needle driving mechanism and a transporter driving mechanism, the lower part of the frame housing a shuttle device and rotating hook for the formation of a loop with the upper thread drawn by the needle and the knotting of this upper thread to a lower thread paid out by the bobbin for sewing with two threads, and comprising a loop-guide element for holding open the loop formed by the rotating hook and for enabling the needle to prick the following stitch through the previous loop held open, so as to effect a chain-stitch sewing, a control lever for the to and fro movements respectively, of the transporter and bearing said loop-guide element, said control lever oscillating around a vertical axle and causing the holding of the loop open in the path of the needle during the pricking of the latter and the retraction of the loop-guide element towards the shuttle for the take up of the new loop being formed and bringing the latter into the path of the needle.

In order that the invention may be more clearly understood there is described below one embodiment of a sewing machine according to the invention, purely by way of illustrative but non-limiting example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view in partial cross-section of the lower arm of a sewing machine according to the invention, of the free arm type, the cross-section showing the shuttle device, the feeding device and the path of the needle.

FIG. 2 is a plan view corresponding to that of FIG. 1.

FIGS. 3 and 4 are plan views similar to that of FIG. 2 showing the mechonism in two other positions of use, FIG. 3 in position for chain-stitch sewing and FIG. 4 in the position for sewing with two threads. I

With reference to the drawings, the sewing machine of which only the lower part of the frame 1 has been shown, comprises in the usual manner a driving mechanism for the vertical to and fro movements of a needle 2, a supporting plate 3 for the pieces to be sewn 4, a fabric pressure-foot 5 holding the pieces to be sewn 4 against the plate 3 and thus against the claw 6 of the transporter or feeding device. This claw 6 is intended to be driven in movement to and fro in the case shown by a lever 7 mounted and oscillating on the vertical axle 8. The end 9 of the lever 7 is connected by a tie-rod -10 to a crankshaft -11 driven from a horizontal shaft 12 and this through the intermediary of a tangential screw 13 and of a pinion 14, the crank 11 turning around a vertical axle v15. The other end 16 of the lever 7 acts through the intermediary of tie-rods 17, 18 respectively, pivoted one to the other, at a point '19 of a lever 20 oscillating, by one of its ends, around a vertical axle 21 of the frame 1. The other end 22 of the lever 20 has a rod 23 around which a support 24 carrying the claw 6 is capable of sliding vertically. The movements in the vertical direction of this claw 6 are controlled by the intermediary of another lever 25 oscillating around a horizontal axle 26 rigidly attached to the frame -1. A cam 27 with axial profile, arranged under the pinion 14, causes the movements of the lever 25 determining the upward and downward displacements respectively of the claw 6.

The sewing machine comprises a shuttle device indicated in a general manner by the numeral 28, comprising a rotating hook 29 in the form of a bowl, pivoting around an axis 30, arranged appreciably vertically. On the interior of the rotating hook 29 is arranged a support 31 having a seating 32 intended to receive the bobbin 48 carrying the lower thread 49 for sewing with two threads (see FIG. 4).

Such a sewing machine therefore enables conventional sewing with two threads, that is to say, in which an upper thread 33 is drawn by the needle 2, the end of the thread 33 pasing through the eye 34 of the needle, being intended to be taken by the hook 29 to form a loop 25 turning around the bobbin 48 carrying the lower thread 49 of the shuttle to knot it to the lower thread. In the embodiment shown in FIGS. 1 to 3, the sewing machine is not provided with a bobbin for carrying lower thread, but this sewing machine comprises a device enabling it to be used for single thread sewing, that is to say chainstitch sewing. For this purpose this sewing machine comprises a loop-guide element indicated in a general manner by the numeral 36, comprising an arm 37 having a forked end 38, in the form of an open V-shaped beak. This arm 37 is elastically mounted at 39 on a supporting plate 40. This plate 40 has two oblong openings 41 and 42 enabling it to engage on two pins 43, 44 respectively, projecting from the lever 7 for driving the transporter. A spring 45 of which one end 46 is hooked to a supporting plate 40 and the other end 47 to the lever 7, ensures the maintenance of the support plate 40, and of the loop-guide element respectively, in one or other of two longitudinal positions on the driving lever 7. These longitudinal positions are determined by the engagement of the pin 43 against the corresponding ends of the oblong openings 41. The pin 43 is constituted, in the particular case, by the upper end of the pivoting axle 8 of the lever 7.

The operation of the sewing machine, provided with the device described above, is as follows: When the loop-guide element is brought into its active active position shown in FIGS. 1, 2 and 3, its beak-shaped end 38 is at a given moment in the operation of the sewing machine in a position such that the inner space of the beak 38 is located in the path of the needle 2 as shown in FIGS. 1 and 2.

When the needle 2 then pricks a stitch the thread 33 drawn by it is taken by the hook 29 which draws it to form a loop 35 passing around the seating 32, this loop 35 then being engaged on the beak 38 of the loop-guide element and being then in the position shown in FIG. 3, that is to say a position removed from the path of the needle 2 and displaced towards the shuttle. The loop 35 is then kept open by the loop-guide element and, particularly, by the beak-shaped forked end 38 of the latter as shown in FIG. 2. On the next stitch-forming cycle of the machine, the loop 35 is brought by the loop-guide element 36, driven by the lever 7 of the transport mechanism, in to the path of the needle 2 which is engaged in this loop 35. The hook 29 then forms the following loop which knots the previous loop, itself relaxed by the withdrawal movement of the beak 38, outside the path of the needle 2, in the direction of the shuttle (see FIG. 3). The following loop, formed by the hook 29, is then taken in its turn by the end 38 of the loop-guide element 36 for the formation of a new stitch of chain-stitch sewing.

The preceding description shows the great simplicity of the conception of this device with a loop-guide element 36 which, once adapted on an ordinary sewing machine for two thread sewing, enables, with the aid of the latter, simple single thread sewing in chain-stitch to be elfected, which can be useful in certain particular sewing jobs, for example for tacking clothing, or other jobs not requiring very strong or long-lasting sewing, but aiming at the decorative effect of the chain-stitch.

Since the loop-guide element 36 is capable of occupying two longitudinal positions with respect to the lever 7, this loop-guide element can be left in the lower arm of the frame 1 of the sewing machine without preventing the use of the latter to effect normal sewing with two threads. In fact, it suffices to displace the loop-guide element 36 towards the right with respect to the drawing, into the position shown in FIG. 4, in order that the beak 38 of the latter is in a position sufficiently removed from the path of the needle 2, on the one hand, and from the path of the hook 29, on the other hand, so that this beak 38 cannot hook a loop 35 of the thread 33, being formed.

I claim:

1. A sewing machine, comprising a supporting frame for a needledriving mechanism and a transporter-driving mechanism, the lower part of the frame housing a shuttle device and rotating hook for the formation of a loop with the upper thread drawn by the needle and the knotting of this upper thread to a lower thread paid out by the bobbin for sewing with two threads, and comprising a loop-guide element for holding open the loop formed by the rotating hook and for enabling the needle to prick the following stitch through the previous loop held open so as to effect a chain-stitch sewing, a control lever for the to and fro movements respectively, of the transporter and bearing said loop-guide element, said control lever oscillating around a vertical axle and causing the holding of the loop open in the path of the needle during the pricking of the latter and the retraction of the loop-guide element towards the shuttle for the take up of the new loop being formed and bringing the latter into the path of the needle.

2. A sewing machine according to claim 1, wherein the loop-guide element comprises an arm having a forked end in the form of an open V-shaped beak.

3. A sewing machine according to claim 1, comprising a support plate attached to said control lever, said loopguide being elastically mounted to said support plate to enable a certain displacement in height of the loopguide element.

4. A sewing machine according to claim 3, comprising fixing means attaching said support plate to the control lever, said fixing means enabling the longitudinal displacement of the loop-guide element with respect to the control lever, between an active position for chain-stitch sewing and an inactive position in which the loop-guide element is spaced from the path of the needle and of the hook, to enable the normal operation of the machine for sewing with two threads.

5. A sewing machine according to claim 4, wherein said fixing means comprises two oblong openings in the support plate, two pins projecting from the lever and engaging said oblong openings and a spring hooked between the lever and the support plate ensuring the maintenance of the latter in one or other of its two longitudinal positions on the control lever.

6. A sewing machine according to claim 5, wherein one of said pins is constituted by the upper end of said vertical axle of the control lever.

7. A sewing machine according to claim 3, wherein said loop-guide element comprises an arm having a forked end in the form of an open V-shaped beak.

8. A sewing machine according to claim 4, wherein said loop-guide element comprises an arm having a forked end in the form an of open V-shaped beak.

9. A sewing machine according to claim 5, wherein said loop-guide element comprises an arm having a forked end in the form of an open V-shaped beak.

10. A sewing machine according to claim 6, wherein said loop-guide element comprises an arm having a forked end in the form of an open V-shaped beak.

References Cited UNITED STATES PATENTS 727,053 5/1903 Anthony 112-168 761,558 5/1904 Toof 112168 809,660 l/l906 Ammerman 112168 2,999,472 9/1961 Yamano 112-168 3,253,560 5/1966 Ketterer et al. 112-l 68 JAMES R. BOLER, Primary Examiner. 

